Field of the Invention
The present invention relates to a filling method and station.
The invention relates more particularly to a method of filling at least one buffer container of a filling station with pressurized gaseous hydrogen, the filling station comprising at least one buffer container and a fluid circuit connected to said at least one buffer container, the circuit of the filling station comprising a first end connected to at least one source of gaseous hydrogen for carrying out the filling of the at least one buffer container with gas originating from the source, the circuit comprising a second end equipped with a transfer pipe intended to be removably connected to a tank, in order to fill said tank from the at least one buffer container.
Related Art
The fast filling (that is to say typically less than 15 minutes) of (hydrogen) gas tanks of vehicles is generally carried out by successive pressure equalizations. That is to say that buffer containers storing gas at increasing high pressures (for example 200, 300, 450 or 850 bar) are successively placed in fluidic communication with the tank to be filled.
These methods are described abundantly in the literature. Reference may for example be made to documents FR 2919375 A1, FR 2973858 A1 and FR 2919375 A1 that describe filling stations to which the present invention may apply.
The hydrogen of the tanks of such vehicles is generally provided in order to supply a fuel cell. The fuel cells (in particular of “PEMFC” type) must be supplied with a very “pure” hydrogen gas. Indeed, a wealth of literature describes the negative impacts of impurities (such as chemical species, water, CO, H2S) in the hydrogen in terms of performance and service life of the fuel cells.
Strict standards have been developed to ensure that the hydrogen delivered to the tanks does not damage the cells (cf. for example the ISO 14687-2 standard).
The standards of industrial gases obtained by virtue of known and relatively inexpensive manufacturing processes do not make it possible to ensure such a degree of purity. It is generally acknowledged that in order to guarantee hydrogen purities that are always compatible with the requirements of fuel cells, it is necessary to add, upstream of the filling stations, steps for purifying the hydrogen gas produced industrially. These purification steps are however expensive (for example purifications over a bed of adsorbent operating at cryogenic temperature or with palladium membranes).
Thus, in order to guarantee a hydrogen purity in accordance with the specifications of fuel cells, one known solution consists in supplying the filling station with liquid hydrogen. This hydrogen is by definition very pure since its temperature (of the order of 20 K) makes all the impurities precipitate in solid form. Another solution consists in using hydrogen purified with adsorber purifiers that operate at a cryogenic temperature. Another solution consists in using hydrogen originating directly from an electrolyzer followed by a step of deoxidation over a catalyst bed and of drying over an adsorbent.
These solutions generally also result in a large additional cost (additional cost of 40% to 100% relative to the cost of the hydrogen produced industrially).
Another known solution uses a gas analyzer installed upstream of the compressors of the filling station in order to verify the purity of the gas. When a threshold of impurities is exceeded in the gas supplied to the compressor, the inlet valves of the compressor(s) are closed which causes the shutdown of the compressor. The filling station is then in degraded mode (filling capacities deliberately reduced in order to conserve operational autonomy). The restarting of the compressor is then in most cases a manual operation, requiring the presence of an operator on site. Furthermore, if the station is supplied by a source of gas that originates from an on-site or decentralized generator, the impure hydrogen (i.e. not in accordance with the specifications) is then emitted into the air in order to allow the system to recover a nominal degree of purity by acting automatically or manually on the hydrogen production parameters. This gives rise to energy wastage.